1. Field of the Invention
The present invention relates to a mammograph equipped with a stereotaxic imaging device with digital detector and a method of using such a mammograph. The field of use of the invention is essentially medical, since mammography makes it possible to detect tumors of the breast and to carry out certain medical treatments.
2. Discussion of the Related Art
A mammograph comprises an X-ray tube, situated at the end of a first arm which can be moved about an axis and emitting X-radiation toward a receiver situated at the end of another arm. A breast support plate and a breast compression plate, holding the breast in place during mammography, are arranged between the tube and the receiver. The image receiver may be a photographic film or a digital receiver, such as a CCD camera. In order to take stereotaxic images, it is necessary for the X-ray tube to be movable in rotation, about the breast support and compression plates, in order to be inclined successively along two opposite orientations on either side of its initial position which is perpendicular to the plane of the image receiver, so that two images are taken by the receiver. By virtue of a stereotaxic location device carrying out the computerized processing of the two images obtained after developing of the photographic frames, the three-dimensional position of a defined region of the breast, where, for example, there is a lesion, is calculated. A mammograph equipped with such a stereotaxic imaging device is described in the European Patent published under number 0,390,653 B1 in the name of the Applicant Company.
In order to reduce the duration of the radiological examination which is relatively painful for the patient, in particular during medical treatments during which it is necessary to develop the photographic film, calculate the position of the region to be treated, and guide the biopsy needle, for example, before ending the compression of the breast, the film is replaced by a digital detector. Digital detectors are currently made from CCD sensors which make it possible to obtain a digitized image of the object examined in a few seconds or hundredths of milliseconds, but which have the disadvantage of having a sensitive surface area of the order of 4 to 10 mm.sup.2, which is too small for application to stereotaxic imaging. It is possible to increase the field of view by using an optical device, such as a combination of lenses or a fiber-optic image reducer. However, despite this, the final field of view remains smaller than that obtained with systems using photographic film, which leads to a reduction in the volume of the object accessible to stereotaxic imaging.